There is a need for safe, effective antibacterial and anti-inflammatory agents for use in oral care compositions. Magnolia extract is known to contain compounds having antibacterial and/or anti-inflammatory properties, and such compounds have been the focus of considerable interest for use in oral care compositions. The use of such compounds in oral care compositions is described, for example, in WO2001/085116, WO 2011/106492 and WO 2011/106493, the contents of which application are incorporated herein by reference. Methods of synthesizing magnolol are disclosed, e,g, in WO 2011/106003. Synthetic non-natural analogs of various components of magnolia extract are also known to have antibacterial activity, but the compounds are in some cases expensive to synthesize.
Magnolol analogs having lower alkyl in place of allyl are of particular interest, as are compounds wherein the alkyl or allyl side chains are ortho rather than para to the hydoxy goups (isomanolols). Tetrahydro-magnolol, (5,5′-dipropyl-biphenyl-2,2′-diol) is a broad spectrum antibacterial and anti-inflammatory agent with potential applications in oral care and personal care products. It has advantages over magnolol, e.g. in that it does not stain toothbrush bristles when used as an antibacterial/anti-inflammatory agent in a toothpaste. Existing synthetic methods for making magnolol derivatives, however, involve costly reagents and yields are low. There is a need for cheaper, higher yield synthetic procedures to make magnolol derivatives.